Epigenetic modification is involved in aberrant expression of class III β-tubulin, TUBB3, in ovarian cancer cells
Epigenetic modification is involved in aberrant expression of class III β-tubulin, TUBB3, in ovarian cancer cells
复制标题
DOI：
10.3892/ijo_32_6_1227
复制
发表时间：
1992-06
影响因子：
5.2
通讯作者：
Naoko Izutsu;C. Maesawa;M. Shibazaki;H. Oikawa;T. Shoji;T. Sugiyama;T. Masuda
中科院分区：
文献类型：
--
作者：
Naoko Izutsu;C. Maesawa;M. Shibazaki;H. Oikawa;T. Shoji;T. Sugiyama;T. Masuda
据报道，III类β-微管蛋白TUBB 3的异常表达是导致多种人类恶性肿瘤中紫杉烷耐药的重要机制之一。我们研究了66个原发性卵巢癌肿瘤和3个卵巢癌细胞系（OVCAR-3、JHOC-5和JHOC-8）中TUBB 3的异常表达及其表观遗传修饰。TUBB 3蛋白在66例卵巢癌中有56例（85%）过度表达，且与肿瘤的侵袭性行为（晚期、有腹水、手术减瘤效果不佳和有淋巴结转移）显著相关（P<0.05）。卵巢癌细胞系对去甲基化剂（5-氮杂-2 '-脱氧胞苷，5-Aza-CdR）和组蛋白去乙酰化酶抑制剂（4-苯基丁酸，PBA）治疗的反应不同。在TUBB 3蛋白表达较弱的2个细胞系（OVCAR-3和JHOC-8）中，5-Aza-CdR（JHOC-8）或PBA（OVCAR-3）处理可独立诱导TUBB 3诱导，而在TUBB 3强表达细胞系（JHOC-5）中，两种药物均未显著改变TUBB 3 mRNA/蛋白表达。内含子1内的CpG岛在1个细胞系（JHOC-8）中被高甲基化，该细胞系弱表达TUBB 3，需要5-Aza-CdR处理以进行基因表达。与显示TUBB 3的组成型表达的细胞系（JHOC-5）类似，显示微弱TUBB 3蛋白表达的另一细胞系（OVCAR-3）的CpG岛被低甲基化，其中通过用PBA处理而不是用5-Aza-CdR处理诱导了TUBB 3表达的显著增加。我们使用甲基化特异性PCR评估了14例原发性肿瘤中该区域的甲基化状态，但与TUBB 3免疫反应性无显著关系。提示TUBB 3蛋白的异常表达可能与卵巢癌的侵袭性行为有关，TUBB 3蛋白的表达可能与表观遗传调控（DNA甲基化和染色质乙酰化）有关。
Aberrant expression of class III beta-tubulin, TUBB3, has been reported to be one of the important mechanisms responsible for taxane resistance in diverse human malignancies. We investigated aberrant TUBB3 expression and its epigenetic modification in 66 primary tumors and 3 cell lines (OVCAR-3, JHOC-5 and JHOC-8) of ovarian cancers. Overexpression of TUBB3 protein was observed in 56 (85%) of the 66 ovarian cancers, and was significantly associated with aggressive tumor behavior (advanced stage, presence of ascites, suboptimal cytoreduction at surgery and presence of lymph node metastasis) (P<0.05). Responses to treatment with a demethylating agent (5-aza-2'-deoxycytidine, 5-Aza-CdR) and a histone deacetylase inhibitor (4-phenylbutyric acid, PBA) differed among the ovarian cancer cell lines. In 2 cell lines with weak expression of TUBB3 protein (OVCAR-3 and JHOC-8), TUBB3 induction was independently induced by treatment with 5-Aza-CdR (JHOC-8) or PBA (OVCAR-3), while neither agent markedly altered TUBB3 mRNA/protein expression in a strongly TUBB3-expressing cell line (JHOC-5). A CpG island within intron 1 was hypermethylated in 1 cell line (JHOC-8) that expressed TUBB3 weakly and required 5-Aza-CdR treatment for gene expression. A CpG island of another cell line showing faint expression of TUBB3 protein (OVCAR-3), in which a significant gain of TUBB3 expression was induced by treatment with PBA but not with 5-Aza-CdR, was hypomethylated, similarly to a cell line (JHOC-5) showing constitutive expression of TUBB3. We evaluated methylation status in this region in 14 primary tumors using methylation-specific PCR, but there was no significant relationship with TUBB3 immunoreactivity. These findings suggest that aberrant expression of TUBB3 protein might be associated with aggressive behavior of ovarian cancers, and that epigenetic modulation (DNA methylation and chromatin acetylation) might be partly involved in TUBB3 expression.